Calculate normal probabilities and determine unknown mean/standard deviation parameters from percentile data.

A box contains a large number of biscuits. The weights of biscuits are normally distributed with mean 7 g and standard deviation 0.5 g.

1. One biscuit is chosen at random from the box. Find the probability that this biscuit[4]
   1. weighs less than 8 g;
   2. weighs between 6 g and 8 g.
2. Five percent of the biscuits in the box weigh less than d grams.[5]
   1. Copy and complete the following normal distribution diagram, to represent this information, by indicating d, and shading the appropriate region.
   2. Find the value of d.
3. The weights of biscuits in another box are normally distributed with mean \(m\) and standard deviation 0.5 g. It is known that 20% of the biscuits in this second box weigh less than 5 g. Find the value of \(m\).[4]